[V8] flickering lights, voltage regulator?

Ed Kellock ekellock at gmail.com
Wed Nov 2 22:37:33 EST 2005

Been at the car with a meter.  Checked at both the jump-start posts
under the hood and at the battery terminals.  Even though I have a
digital meter, the fluctuation was observable.  The good news is the
readings at both places were between 13.9 and 14.2 volts.  I even
checked the climate control readout and saw readings there consistent
with the other two sites.

Car is fully warmed up with all consumers turned off and no clicking
observed anywhere.

I did loosen and work the battery cable connections back and forth to
possibly refresh the connection.  Also pulled the battery caps and all
cells were up to an acceptable level.  There was a very small amount
of moisture evident before removing the caps (two long ones that cover
3 cells each.)  Vent tube is present and clear.

Battery is an Interstate Megatron MT-93 850 cca.  It was in the car
when I bought it in June of '99.  The car just sat for a month in the
parking garage at work without being used.  I did go down and start it
and drive around the lot a couple times maybe twice during the month.
Never had any evidence of a weak battery.

It just so happens that I have another of the exact same battery in
the garage.  I pulled it from a car at the junkyard about 4-6 weeks
ago, dead as a doornail, but looking very new.  I brought it home and
have trickle-charged it off and on since and it will now hold just
over 12+ volts in between trickle-charges.  I could swap it if that
seems a reasonable measure.

Still, seems to me there's a charging system fluctuation.  One
previous suggestion was "could you have a bad connection to the field
line to the alternator?"  I can go under the car later in the week to
check this.  What exactly might I be looking for to do so?

The flickering is not present without the car running, is present
without any electical consumers on, varies with engine speed, and is
still present with electrical consumers on.


----- Original Message ----- 
From: "Ed Kellock" <ekellock at gmail.com>
To: <v8 at audifans.com>
Sent: Wednesday, November 02, 2005 7:33 PM
Subject: Re: [V8] flickering lights, voltage regulator?

> Just revisited this tonight when I brought the car home from
> in the parking garage at work after a month.  The flickering changes
> with engine rpm.  The alternator was replaced with a Bosch reman
> almost exactly 2 years ago.  I've noticed this flickering for a
> now.
> Going to go out with a meter and see what I can see.
> Ed
> ----- Original Message ----- 
> From: "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>
> To: "V8" <v8 at audifans.com>
> Sent: Wednesday, October 19, 2005 3:43 PM
> Subject: Re: [V8] flickering lights, voltage regulator?
> > ... one key piece of information is whether or not the fluctuation
> > frequency varies as a function of the engine speed.  If it does
> that
> > does not completely exonerate the alternator, but it does tend to
> cause
> > one to consider other possibilities ...
> >
> > ... could you have a bad connection to the field line to the
> alternator?
> > ... is there possibly some load that is switching on and off in a
> > rhythmic fashion ... say something like the A/C Compressor clutch
> > some other high load item ... seat heater perhaps?
> >
> > IME alternators are pretty robust and consistent in their
> > That said, I have replaced the alternator on one of my V8s ...
> >
> > Good luck!
> > Steve B
> > San Jose, CA (USA)
> > >
> > > I just went down to the parking garage. The condition exists
> > regardless of
> > > whether the headlights are on. I was struggling to think of a
> better
> > term
> > > than flicker. It's more of a pulsation, barely noticeable, but
> > > imperceptible. If it's not dark you can still see it but
> you
> > have
> > > to kind of blur your vision and look just to the side. This was
> all
> > based on
> > > my observation of my center dome light.
> > >  I think I'm going to go after the voltage regulator. In a
> > unit, it
> > > may have been given only quick consideration and thought good.
> I'll
> > see what
> > > tests I can run on it.
> >
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